The Contractor shall exert its best efforts to evaluate an approach to the immunotherapy of cancer in rats utilizing L-phenylalanine mustard (PhM). These studies will be done with at least two different syngeneic rat tumorsand shall follow in vivo therapy protocols previously devised by the investigator for allogeneic tumors. The experiments to be conducted shall include intra-tumoral injection of phenylalanine mustard (PhM) plus I.V. injection of anti-serum against PhM conjugated extract of the tumor being studies. Suitable controls for each of the injected materials in different groups of rats shall be used, and both tumor size and survival shall be evaluated. Suitable histologic studies shall be performed. Tumor specificity of any response observed shall be evaluated in the in vivo system.